Downlights and spotlights are in very widespread use by architects, interior designers as well as end-users for creating a desired interior style.
Downlights are generally used for general illumination purposes and usually produce a relatively broad beam, whereas spotlights are typically aimed at a certain target by tilting and rotating the spotlight.
Recently, advances in lighting technology, especially in the field of light emitting diodes (LEDs) and LED-based luminaires, have enabled flat and compact light output devices, such as luminaires, which are easier to install and more compact and unobtrusive than conventional lighting systems.
For downlights, the use of this new type of flat luminaires is relatively straightforward. For spotlights, however, mechanical arrangements are needed for controlling the direction of the light output, and these can be relatively bulky.
FIG. 1a schematically illustrates a flat and compact downlight 1, which is mounted on a ceiling 2 to emit light straight down. Such a downlight 1 may, for example, be based on semiconductor light-sources, such as LEDs, and a light-guide arrangement for conditioning (mixing and distributing) the light emitted by the light-sources.
FIG. 1b schematically illustrates a conventional spotlight 3, which is mounted on the ceiling 2 via an ordinary mechanical beam direction controlling device 4. By manually tilting and rotating the spotlight 3, the direction of the light-beam 5 emitted thereby can be controlled at will.
If one would straightforwardly combine the flat and compact downlight 1 in FIG. 1a with the mechanical beam direction controlling device 4 in FIG. 1b, one would arrive at a spotlight based on the flat downlight 1 in FIG. 1a and the mechanical housing of FIG. 1b. However, many of the features of the downlight 1 in FIG. 1a that make it attractive for deployment in various lighting solutions would then be lost.
In order to provide a user controllable spotlight while maintaining many of the attractive features of the downlight 1 in FIG. 1a, various embodiments of beam direction controlling device are known, for example as schematically shown in FIG. 2, which shows a light-output device in the form of a controllable spotlight comprising a flat and compact light-emitting device 1 similar to the downlight 1 in FIG. 1a and an optical beam direction controlling device 6 arranged such that light emitted by the light emitting device 1 passes through the beam direction controlling device when the spotlight is in operation.
WO2010/041182 discloses an arrangement as shown in FIG. 2 in which the beam direction controlling device 6 for example comprises first 7 and second 8 optical elements, each of which is moveable in a plane parallel to the ceiling 2 using first and second actuators, by which the user can move the first and second optical elements independently of each other. Through operation of the actuators the direction of the light beam 9 emitted by the spotlight can be controlled.
This type of arrangement enables integration into a flat luminaire, but the optical elements reduce the optical efficiency of the system compared to a mechanical alignment solution.
There is therefore a need for a mechanical beam steering approach which can be made compact and easy to use.